1. Field of the Invention
The present invention generally relates to gas service connections and methods of repairing the same. More particularly, the present invention relates to improved methods and equipment for inspecting, relining, disconnecting and/or reconnecting gas service lines and gas service connections.
2. Brief Description of the Background Art
It is commonly desirable to physically access gas service lines for a wide variety of reasons. One such reason results from the previous construction of service lines from iron or ferrous alloy pipe. The choice of pipe may previously have been for reasons of economy or requirements of strength, local statutes or zoning requirements. This is still true, even though some localities now permit service lines to be constructed from, for example, plastic piping and the like. However, older and therefore more common iron pipes have, in most areas, been used in service for extended lengths of time and so, are now found to be in accelerated states of decay. In most instances, stress faults and corrosion are found in these pipes to be in at least nascent states, if not actually advanced throughout the gas service. The service then requires some form of repair or replacement so as to effectively preclude the corrosive perforation of any part of the line, in order to best ensure the continued safety and welfare of the public.
In addition, in order to plug or seal the gas service lines, access is required, for example, in order to discontinue service to delinquent customers or to those who may have temporarily or permanently converted to alternate forms of utility service. Access to service lines is also required in order to physically sever the service from the main in the event, for example, that the building or structure to which the service supplies gas is to be vacated, demolished or, of course, moved.
In order to safely perform any maintenance, repairs or other work on service lines, it is obviously necessary to be able to shut off the supply of incoming gas so as to prevent any inadvertent leakage. Heretofore, it has generally been necessary to dig about and isolate the gas main at the area in which it is connected to the service line. The connection between the main and the service is known as a "tee", and nearly always includes a shut-off valve. After the tee is closed, the service line may then be accessed or breached and worked on as may be necessary.
It is known to those acquainted with this art that the above-described isolation procedure is an extremely expensive undertaking in nearly all aspects. Initially, local municipalities require construction permits for excavation. These permits often cost up to about $200.00 or more, each. Additionally, gas mains are usually located approximately six feet below ground level and often run both parallel to and beneath existing roadways. Since these gas mains have been laid under roadway surfaces, asphalt, brick, concrete and the like must be removed in order to isolate the service tee. Further, since these gas mains have often been installed in early communities in early 1900s, and sometime even in the previous century, precise and exact knowledge of their where to best dig for the gas main itself is often a matter of guesswork, let alone the decision of where along the main to locate the service line tee. Accordingly, these procedures are not jobs to be taken lightly, especially in cold, hot or even mildly inclement weather and certainly not be attempted at all in sub-zero temperature conditions.
Although not affecting either the physical condition of the service line or the gas main, it is also necessary to shut off the gas flow when replacing a defective gas flow meter or removing one for service. This can, however, generally be accomplished from inside the gas-supplied structure without disrupting any of the service line, the roadway or the surrounding neighborhood. However, interrupting the service for such a temporary event does result in significant repercussions in that the gas lines within the structure must now be bled of atmospheric air and, of course, each service pilot which is fed off those lines must then be relit. The bleeding procedure often cannot be properly accomplished in one visit within any reasonable length of time and so multiple repeated service calls are required. This unavoidably results in both unnecessary consumer aggravation and increased utility expense. Thus, the various requirements of diverting commercial traffic, providing alternate access for local traffic and the expense of restoring the roadway surface to at least its former state, as well as the necessity of repeatedly rescheduling the return of work crews to previous job sites in order to correct earlier work has provided the impetus for the present invention.